I've got an old 2U dell office machine with:
CPU: Intel i7 3770 4c/8t
iGPU: Intel HD 4000
RAM: 16gb 1600mhz
NIC: Intel 82579LM
SSD: 120gb (boot)
HDD: 12tb, 500gb
OS: Ubuntu 20.04.1 LTS
Services: SMB, QBitTorrent, JDownloader2
I've been using it as a 24/7 NAS, SeedBox and filehost downloader for about a year now with the 12tb drive for torrents and the 500gb drive as scratch space for things saved through JDownloader. Which mounts as a CIFS network drive on my main machine so FFMPEG can transcode whatever is on it before saving it to my archival drive.
I've become comfortable with this setup but I quickly realized that this is way overkill for what I've been doing with it and have been wondering for a while if there are any applications or services that I could run on it. I've considered hosting a Mineclone or Veloran server for online aquaintances to get on together but I don't have a reverse proxy to put my dynamic IP behind.
I also have an old low power thin client HP Greenwood motherboard with
CPU: AMD e1-6015
iGPU: r2 HD 8240
RAM: 8gb 1333mhz
NIC: Realtek RTL8106E-CG
That I used to use as an HTPC booting LibreElec and running Kodi with only 1gb of RAM before we got a new AndroidTV puck to run it off of. It only runs at about 20w but the APU in it is shit for anything that isn't an embedded type of task and the NIC is only 10/100. Plus there's almost 0 expandability, only a mini PCIE 2.0 1x slot and 2 sata ports. So the most I could put on it is a single 3.5" HDD and a single 2.5" SSD with a 15 pin slimline to 22 pin sata adapter and maybe a mini PCIE network card/riser. Plus a case for it all. Which all included would cost more than what the board is worth. But I've also wondered what I could run off of it since I don't like having hardware just sit around doing nothing.